The environmental concerns regarding availability of water for any purpose, especially for sewage disposal, and of disposing of water used for sewage purposes, has led to severe limitations on the amount of water which is permitted for each flush of a commode. Historically commode flushing systems were permitted to use whatever amount of water was convenient to flush the commode and reliably remove the contents of the bowl. Cycles using several gallons were acceptable.
Now that has profoundly changed. In certain areas crowded with people, the resulting demand for water and the amount of effluent they generate seriously compromise the availability of the water and of the disposal plants which ultimately receive it. As a consequence, governmental units regularly require that new commode installations be reliably flushed with only a few quarts of water, instead of gallons.
A properly designed commode can indeed flush reliably with such a short flush, but only if it is reliably supplied, each time, with a known and specified volume of water delivered under known and specified conditions. However, conventional commode supply and flush systems are susceptible to substantial variations not only from installation to installation, but from flush to flush in the same installation. This makes it most difficult for a manufacturer to design a product for a short flush which is reliable under all circumstances.
It is an object of this invention to provide a flush and fill system for a commode tank whose delivery is volumetrically consistent regardless of differences or variations in water supply pressure or re-supply rates of flow.
In the conventional art, a commode tank is filled and kept closed and at rest until a flush cycle is started. When it is, a flush valve in the bottom of the tank is opened and the contents of the tank are discharged into the commode. The problem arises that with a conventional float-controlled supply valve, the supply valve opens to re-supply the tank even while the tank is emptying, because the float valve which follows the surface of the water in the tank as the tank empties opens the valve before the tank is emptied.
Such an arrangement is tolerable if one can assume that the flow rate of re-supply is consistent and known relative to the rate of discharge from the tank to the commode. This is far from a reliable assumption. Especially for short flushes, variations in water supply pressures and related flow rates can cause the amount of water actually delivered in a given period of time to vary as much as 30% above and below that which is needed for an optimum flush. Such variations either way from an optimum flush are undesirable. Too little water can make an insufficient flush, which will require a subsequent flush thereby wasting water. Too much wasted water frustrates the very purpose of having a short flush commode in the first place.
This invention overcomes the disadvantages of the prior art by requiring that the contents of the tank at rest be delivered to the commode before refilling of water to the tank is started. Deferral of refilling is not per sea new concept. For example, see Antunez U.S. Pat. No. 4,840,196 issued Jun. 29, 1989. However the invention contemplated in that patent involves a complexity of valving concepts which it is an object of this invention to overcome, and which will permit the use of known and proved conventional tank valves.